The present invention relates to a liquid crystal display apparatus, more particularly relates to a liquid crystal display apparatus provided with a liquid crystal display with a luminance which is adjusted using a backlight.
A liquid crystal display apparatus and 30 is provided with, for example, as shown in FIG. 1, a timing signal generation circuit 31 which generates a timing signal when supplied with a horizontal/vertical synchronization signal; a liquid crystal display 32 in which transparent electrodes are arranged in the form of matrix to form pixels; a column driver 33 which is supplied with a video signal and drives the electrodes of the pixels of every horizontal line of the liquid crystal display 32 at the video signal level of a the respective pixels; a line driver 34 which drives the pixels for each of the horizontal lines; and a backlight 35 which irradiates light from the back surface to the main surface of the liquid crystal display 32.
In the liquid crystal display apparatus 30, in a state where light is irradiated to the liquid crystal display 32 from the backlight 35, the column driver 33 and the line driver 34 are synchronized by a timing signal, and a video image is output from the liquid crystal display 32 by the video signal of every pixel supplied with the video signal level by the column driver 33, to the pixels of every horizontal line sequentially driven by the line driver 34.
In the liquid crystal display apparatus 30, however, when the video signal level is small, the video signal level is amplified or the zero level of the video signal level is raised in accordance with the video signal level, whereby the video signal level is brought to a high level and the video image is output from the liquid crystal display 32. However, where the video signal level is amplified when the video signal level is extremely small, the amplification rate becomes extremely large, a distortion occurs in the video signal, and there arise problems that the quality of the image is deteriorated or the output image unnaturally changes at the switching of the amplification rate. Also, where the zero level is raised, there arises a problem that there are few color tones which can be displayed and deterioration of the image such as pseudo contours occur.
Also, in the liquid crystal display apparatus 30, when the video signal level of the video signal transitionally changes such as for example at the time of selection of a station, when the power source voltage is turned ON/OFF, etc., by outputting the image while fixing the video signal level to a black level etc., the quality of the picture of the output image of the liquid crystal display 32 is improved.
However, the column driver 33 of the liquid crystal display 32 and the line driver 34 are driven by the black signal level etc. and the backlight 35 is turned on, therefore there arises a problem that the power consumption is large.